#Security Context Enforcement Policy
This guide demonstrates how to configure Kyverno to enforce proper security contexts for containers, ensuring they run with appropriate security settings and restrictions.
#TOC
#What is Security Context Enforcement?
Security context enforcement involves controlling how containers run by setting security-related parameters. Proper security context configuration prevents:
- Root privilege escalation: Containers running as root user
- Privilege escalation attacks: Containers gaining elevated permissions
- Insecure process execution: Containers running with dangerous capabilities
- Filesystem tampering: Containers with writable root filesystems
- Security bypass: Containers circumventing security mechanisms
#Quick Start
#1. Require Non-Root Containers Policy
apiVersion: kyverno.io/v1
kind: ClusterPolicy
metadata:
name: require-run-as-nonroot
annotations:
policies.kyverno.io/title: Require Run As Non-Root User
policies.kyverno.io/category: Pod Security Standards (Restricted)
policies.kyverno.io/severity: medium
policies.kyverno.io/subject: Pod
policies.kyverno.io/description: >-
Containers must run as a non-root user. This policy ensures runAsNonRoot is set to true.
spec:
validationFailureAction: Enforce
background: true
rules:
- name: run-as-non-root
match:
any:
- resources:
kinds:
- Pod
validate:
message: >-
Running as root is not allowed. Either the field spec.securityContext.runAsNonRoot
must be set to true, or the field spec.containers[*].securityContext.runAsNonRoot
must be set to true.
anyPattern:
- spec:
securityContext:
runAsNonRoot: "true"
- spec:
containers:
- securityContext:
runAsNonRoot: "true"#2. Test the Policy
# Apply the policy
kubectl apply -f require-run-as-nonroot.yaml
# Try to create a container explicitly running as root (should fail)
cat <<EOF | kubectl apply -f -
apiVersion: v1
kind: Pod
metadata:
name: test-root
spec:
containers:
- name: nginx
image: nginx
securityContext:
runAsUser: 0
runAsNonRoot: false
EOF
# Try to create a container with non-root user (should work)
cat <<EOF | kubectl apply -f -
apiVersion: v1
kind: Pod
metadata:
name: test-nonroot
spec:
securityContext:
runAsNonRoot: true
runAsUser: 1000
containers:
- name: nginx
image: nginx
EOF
# Clean up
kubectl delete pod test-root test-nonroot --ignore-not-found#Core Security Context Policies
#Policy 1: Disallow Privilege Escalation
Prevent containers from escalating privileges:
apiVersion: kyverno.io/v1
kind: ClusterPolicy
metadata:
name: disallow-privilege-escalation
annotations:
policies.kyverno.io/title: Disallow Privilege Escalation
policies.kyverno.io/category: Pod Security Standards (Restricted)
policies.kyverno.io/severity: medium
policies.kyverno.io/subject: Pod
policies.kyverno.io/description: >-
Privilege escalation, such as via set-user-ID or set-group-ID file mode, should not be allowed.
spec:
validationFailureAction: Enforce
background: true
rules:
- name: privilege-escalation
match:
any:
- resources:
kinds:
- Pod
validate:
message: >-
Privilege escalation is disallowed. The fields
spec.containers[*].securityContext.allowPrivilegeEscalation,
spec.initContainers[*].securityContext.allowPrivilegeEscalation,
and spec.ephemeralContainers[*].securityContext.allowPrivilegeEscalation
must be set to false.
pattern:
spec:
=(ephemeralContainers):
- securityContext:
allowPrivilegeEscalation: "false"
=(initContainers):
- securityContext:
allowPrivilegeEscalation: "false"
containers:
- securityContext:
allowPrivilegeEscalation: "false"#Policy 2: Require Specific User ID Range
Ensure containers run with specific user IDs:
apiVersion: kyverno.io/v1
kind: ClusterPolicy
metadata:
name: require-user-id-range
annotations:
policies.kyverno.io/title: Require User ID Range
policies.kyverno.io/category: Pod Security Standards (Restricted)
policies.kyverno.io/severity: medium
policies.kyverno.io/subject: Pod
policies.kyverno.io/description: >-
Containers must run with a specific user ID range to prevent privilege escalation.
spec:
validationFailureAction: Enforce
background: true
rules:
- name: user-id-range
match:
any:
- resources:
kinds:
- Pod
validate:
message: >-
Containers must run with user ID between 1000 and 65535.
deny:
conditions:
any:
# Check pod-level security context
- key: "{{ request.object.spec.securityContext.runAsUser || 0 }}"
operator: LessThan
value: 1000
- key: "{{ request.object.spec.securityContext.runAsUser || 0 }}"
operator: GreaterThan
value: 65535
# Check container-level security contexts
- key: "{{ request.object.spec.containers[?securityContext.runAsUser && (securityContext.runAsUser < `1000` || securityContext.runAsUser > `65535`)] | length(@) }}"
operator: GreaterThan
value: 0#Policy 3: Require Non-Root Groups
Ensure containers run with non-root group IDs:
apiVersion: kyverno.io/v1
kind: ClusterPolicy
metadata:
name: require-non-root-groups
annotations:
policies.kyverno.io/title: Require Non-Root Groups
policies.kyverno.io/category: Pod Security Standards (Restricted)
policies.kyverno.io/severity: medium
policies.kyverno.io/subject: Pod
policies.kyverno.io/description: >-
Containers should be required to run with a non-root group ID or supplemental groups.
spec:
validationFailureAction: Enforce
background: true
rules:
- name: non-root-groups
match:
any:
- resources:
kinds:
- Pod
validate:
message: >-
Containers must run with non-root group ID. Either spec.securityContext.runAsGroup
or spec.containers[*].securityContext.runAsGroup must be set and not be 0.
deny:
conditions:
any:
# Check if pod-level runAsGroup is 0
- key: "{{ request.object.spec.securityContext.runAsGroup || 0 }}"
operator: Equals
value: 0
# Check if any container has runAsGroup set to 0
- key: "{{ request.object.spec.containers[?securityContext.runAsGroup == `0`] | length(@) }}"
operator: GreaterThan
value: 0#Policy 4: Restrict Seccomp Profiles
Enforce secure seccomp profiles:
apiVersion: kyverno.io/v1
kind: ClusterPolicy
metadata:
name: restrict-seccomp-strict
annotations:
policies.kyverno.io/title: Restrict Seccomp (Strict)
policies.kyverno.io/category: Pod Security Standards (Restricted)
policies.kyverno.io/severity: medium
policies.kyverno.io/subject: Pod
policies.kyverno.io/description: >-
Seccomp profile must be explicitly set to one of the allowed values.
Both the Unconfined profile and the absence of a profile are prohibited.
spec:
validationFailureAction: Enforce
background: true
rules:
- name: seccomp-strict
match:
any:
- resources:
kinds:
- Pod
validate:
message: >-
Use of custom Seccomp profiles is disallowed. The field
spec.securityContext.seccompProfile.type must be set to RuntimeDefault or Localhost.
anyPattern:
- spec:
securityContext:
seccompProfile:
type: RuntimeDefault
- spec:
securityContext:
seccompProfile:
type: Localhost
- spec:
containers:
- securityContext:
seccompProfile:
type: RuntimeDefault
- spec:
containers:
- securityContext:
seccompProfile:
type: Localhost#Policy 5: Require Dropping ALL Capabilities
Ensure containers drop all capabilities:
apiVersion: kyverno.io/v1
kind: ClusterPolicy
metadata:
name: require-drop-all-capabilities
annotations:
policies.kyverno.io/title: Require Drop ALL Capabilities
policies.kyverno.io/category: Pod Security Standards (Restricted)
policies.kyverno.io/severity: medium
policies.kyverno.io/subject: Pod
policies.kyverno.io/description: >-
Containers must drop all capabilities and only add back those that are specifically needed.
spec:
validationFailureAction: Enforce
background: true
rules:
- name: require-drop-all
match:
any:
- resources:
kinds:
- Pod
validate:
message: >-
Containers must drop ALL capabilities.
foreach:
- list: request.object.spec.[ephemeralContainers, initContainers, containers][]
deny:
conditions:
all:
- key: ALL
operator: AnyNotIn
value: "{{ element.securityContext.capabilities.drop || `[]` }}"#Policy 6: Restrict AppArmor Profiles
Control AppArmor profile usage:
apiVersion: kyverno.io/v1
kind: ClusterPolicy
metadata:
name: restrict-apparmor-profiles
annotations:
policies.kyverno.io/title: Restrict AppArmor Profiles
policies.kyverno.io/category: Pod Security Standards (Baseline)
policies.kyverno.io/severity: medium
policies.kyverno.io/subject: Pod
policies.kyverno.io/description: >-
On supported hosts, the runtime/default AppArmor profile is applied by default.
The baseline policy should prevent overriding or disabling the default AppArmor profile.
spec:
validationFailureAction: Enforce
background: true
rules:
- name: apparmor-profiles
match:
any:
- resources:
kinds:
- Pod
validate:
message: >-
AppArmor profile must be set to runtime/default or a custom profile.
Unconfined profiles are not allowed.
pattern:
metadata:
=(annotations):
=(container.apparmor.security.beta.kubernetes.io/*): "!unconfined"#Advanced Scenarios
#Scenario 1: Environment-Specific Security Contexts
Different security requirements for different environments:
apiVersion: kyverno.io/v1
kind: ClusterPolicy
metadata:
name: environment-security-contexts
spec:
validationFailureAction: Enforce
background: true
rules:
# Production: Strict security contexts
- name: production-strict-security
match:
any:
- resources:
kinds:
- Pod
namespaces:
- production
- prod-*
validate:
message: "Production environments require strict security contexts"
pattern:
spec:
securityContext:
runAsNonRoot: "true"
runAsUser: "1000-65535"
runAsGroup: "1000-65535"
seccompProfile:
type: RuntimeDefault
containers:
- securityContext:
allowPrivilegeEscalation: "false"
readOnlyRootFilesystem: "true"
runAsNonRoot: "true"
capabilities:
drop:
- ALL
# Development: Basic security requirements
- name: development-basic-security
match:
any:
- resources:
kinds:
- Pod
namespaces:
- development
- dev-*
- staging
validate:
message: "Development environments require basic security contexts"
pattern:
spec:
containers:
- securityContext:
allowPrivilegeEscalation: "false"
runAsNonRoot: "true"#Scenario 2: Application-Specific Security Contexts
Different security contexts for different application types:
apiVersion: kyverno.io/v1
kind: ClusterPolicy
metadata:
name: application-security-contexts
spec:
validationFailureAction: Enforce
background: true
rules:
# Database applications: Specific user/group IDs
- name: database-security-context
match:
any:
- resources:
kinds:
- Pod
selector:
matchLabels:
app.type: database
validate:
message: "Database applications must use specific security contexts"
pattern:
spec:
securityContext:
runAsUser: "999"
runAsGroup: "999"
fsGroup: "999"
containers:
- securityContext:
runAsNonRoot: "true"
readOnlyRootFilesystem: "true"
# Web applications: Standard security context
- name: web-app-security-context
match:
any:
- resources:
kinds:
- Pod
selector:
matchLabels:
app.type: web
validate:
message: "Web applications must use standard security contexts"
pattern:
spec:
containers:
- securityContext:
runAsNonRoot: "true"
allowPrivilegeEscalation: "false"
capabilities:
drop:
- ALL
add:
- NET_BIND_SERVICE#Scenario 3: Graduated Security Context Enforcement
Implement progressive security context requirements:
apiVersion: kyverno.io/v1
kind: ClusterPolicy
metadata:
name: graduated-security-contexts
spec:
validationFailureAction: Enforce
background: true
rules:
# Level 1: Basic security (all namespaces)
- name: basic-security-level
match:
any:
- resources:
kinds:
- Pod
exclude:
any:
- resources:
namespaces:
- kube-system
- kyverno
validate:
message: "All containers must have basic security contexts"
pattern:
spec:
containers:
- securityContext:
allowPrivilegeEscalation: "false"
# Level 2: Enhanced security (sensitive namespaces)
- name: enhanced-security-level
match:
any:
- resources:
kinds:
- Pod
namespaces:
- finance-*
- hr-*
- security-*
validate:
message: "Sensitive namespaces require enhanced security contexts"
pattern:
spec:
securityContext:
runAsNonRoot: "true"
containers:
- securityContext:
readOnlyRootFilesystem: "true"
capabilities:
drop:
- ALL
# Level 3: Maximum security (critical namespaces)
- name: maximum-security-level
match:
any:
- resources:
kinds:
- Pod
namespaces:
- critical-*
- payment-*
validate:
message: "Critical namespaces require maximum security contexts"
pattern:
spec:
securityContext:
runAsNonRoot: "true"
runAsUser: "1000-1999"
runAsGroup: "1000-1999"
seccompProfile:
type: RuntimeDefault
containers:
- securityContext:
allowPrivilegeEscalation: "false"
readOnlyRootFilesystem: "true"
runAsNonRoot: "true"
capabilities:
drop:
- ALL#Testing and Validation
#Test Root Container (Should Fail)
cat <<EOF | kubectl apply -f -
apiVersion: v1
kind: Pod
metadata:
name: test-root-user
spec:
containers:
- name: test
image: nginx
securityContext:
runAsUser: 0
EOF#Test Privilege Escalation (Should Fail)
cat <<EOF | kubectl apply -f -
apiVersion: v1
kind: Pod
metadata:
name: test-privilege-escalation
spec:
containers:
- name: test
image: nginx
securityContext:
allowPrivilegeEscalation: true
EOF#Test Missing Capabilities Drop (Should Fail)
cat <<EOF | kubectl apply -f -
apiVersion: v1
kind: Pod
metadata:
name: test-missing-drop-all
spec:
containers:
- name: test
image: nginx
securityContext:
capabilities:
add:
- NET_ADMIN
EOF#Test Valid Secure Container (Should Pass)
cat <<EOF | kubectl apply -f -
apiVersion: v1
kind: Pod
metadata:
name: test-secure-context
spec:
securityContext:
runAsNonRoot: true
runAsUser: 1000
runAsGroup: 1000
seccompProfile:
type: RuntimeDefault
containers:
- name: test
image: nginx
securityContext:
allowPrivilegeEscalation: false
readOnlyRootFilesystem: true
runAsNonRoot: true
runAsUser: 1000
capabilities:
drop:
- ALL
add:
- NET_BIND_SERVICE
EOF